Extended Forecast Discussion NWS Weather Prediction Center College Park MD 327 PM EDT Fri Mar 31 2023 Valid 12Z Mon Apr 03 2023 - 12Z Fri Apr 07 2023 ...Strong winter storm to bring strong winds and heavy snow from the north-central Rockies across the northern Plains through Lake Superior Monday into Wednesday... ...Heavy rainfall and severe thunderstorms from the South into the Midwest Tuesday, lingering rest of the week over the South... ...Winter cold for the West and North-central U.S. through this week to starkly contrast summer heat that shifts east from the South to the East/Southeast through midweek... ...Synoptic Overview... Powerful winter storm centered over the Great Basin Monday ejects east-northeast, reaching the north-central Rockies Monday night, crossing the north-central Plains through Tuesday before crossing Lake Superior Wednesday. A reinforcing trough trails this system, likely maintaining troughing over the western U.S. through the rest of the work week and maintaining active weather over the southeast U.S. states. Expect a broad area of significant/hazardous winter weather to areas from the Rockies eastward with the main storm with that and the reinforcing low maintaining a large area of well below normal temperatures from the West through the northern Plains. Expect a large swath of heavy snow north of the low track across the northern Plains and Upper Midwest/Great Lakes along with possible blizzard conditions. This is in stark contrast to widespread convective warm sector showers/thunderstorms to develop and spread across the eastern half of the country that includes a threat for severe weather with a Mid-South focus Tuesday as per the Storm Prediction Center (SPC). Upper ridging over the Gulf Coast should build northward over the eastern U.S. and support anomalous warmth ahead of the storm's associated cold front. This pattern may lead to the stalling of the trailing front into later next week across the U.S. southern tier. Frontal wave enhancements with the ejection of southern stream upper energies may focus convergence/convection and potential training/flash flooding issues, especially from Texas across the lower Mississippi Valley. ...Model Guidance/Predictability Assessment... Confidence further increases in the main and reinforcing systems and associated threats next week. Forecast clustering is best Monday-Wednesday when preference is for a composite of the 06 UTC GFS and 00 UTC ECMWF/UKMET/CMC models for deterministic details. Forecast spread slowly increases into later next week, particularly with the placement and strength of the reinforcing trough axis over the West, lending transition to a preference for the more run to run consistent 06 UTC GFS/GEFS and 00 UTC ECMWF/ECENS along with the 13 UTC National Blend of Models (NBM). The 12 UTC deterministic guidance (GFS/ECMWF/CMC) has come into better agreement with this system with a more positively-tilted trough over the Southwest along with a potentially cutoff low off Southern California Thursday. ...Weather/Hazards Highlights... The big headline is the deepening Plains low that shifts over the north-central Rockies Monday night with strong winds and heavy snow that spill across the north-central Great Plains Monday night through Tuesday night north of a lee-side low pressure system. Probabilities for heavy snow steadily increase from the north-central Rockies along a main axis from southern/eastern Wyoming across much of South Dakota/eastern portions of North Dakota and then across northern Minnesota Monday night into Wednesday. This storm will also produce strong winds, with best potential for the highest wind speeds extending from the Southwest through southern High Plains and northward through the northern Plains where blizzard conditions are likely. Other areas farther east may see brisk to strong winds even if to a less extreme degree. Numerous showers and thunderstorms are likely from the Gulf Coast to the Midwest Tuesday, continuing Wednesday into Friday over Texas and the Southeast as this reinforcing trough maintains a positive tilt to the upper trough with continued advection of copious Gulf moisture and instability over a stalling boundary near the central Gulf Coast. An excessive rain threat increases across Texas through the Southeast Wednesday through Friday. Also the threat of strong to severe storms is increasing in the expansive warm sector, with the Storm Prediction Center highlighting and area on Tuesday. A pronounced temperature contrast will persists across the nation early-mid week with well below average readings spreading across much of the western U.S. and central/northern Plains, and well above average temperatures expanding from the southern Plains/Gulf Coast through much of the eastern U.S. Tuesday-Wednesday look to be the coldest days versus normal over the West/Plains with some areas seeing highs as much as 20-30F below normal. The reverse will hold true over the southern Plains early in the week and farther eastward thereafter, with highs generally 10-20F above normal and lows 15-25F above normal. Daily records mainly for cold highs will be possible over the West during the first half of the week. Farther east in the warm sector, Tuesday-Thursday will offer the best potential for some daily records, with warm lows tending to be more numerous than record highs until the cold frontal passage. Jackson Additional 3-7 Day Hazard information can be found on the WPC medium range hazards outlook chart at: https://www.wpc.ncep.noaa.gov/threats/threats.php WPC medium range 500mb heights, surface systems, weather grids, quantitative precipitation, experimental excessive rainfall outlook, winter weather outlook probabilities and heat indices are at: https://www.wpc.ncep.noaa.gov/medr/5dayfcst500_wbg.gif https://www.wpc.ncep.noaa.gov/medr/5dayfcst_wbg_conus.gif https://www.wpc.ncep.noaa.gov/5km_grids/5km_gridsbody.html https://www.wpc.ncep.noaa.gov/qpf/day4-7.shtml https://www.wpc.ncep.noaa.gov/#page=ero https://www.wpc.ncep.noaa.gov/wwd/pwpf_d47/pwpf_medr.php?day=4 https://www.wpc.ncep.noaa.gov/heat_index.shtml